The comparative study of antibacterial activity from edible mushroom Laetiporus sulphureus (Bull.Fr.) Murill from three localities using bioautographic method

The aim of this study was to obtain preliminary results on the antibacterial activity of edible mushroom Laetiporus sulphureus. Since ethanolic extract of the mushroom was already established to possess good antimicrobial activity, herein we report the antibacterial activity of methanolic extracts out of three different localities. Four Gram-negative and four Grampositive bacterial strains, which are known as human, animal and plant pathogens were used to determine the activity. Bioautography on TLC plates was the method of choice since it is inexpensive, results have a good degree of reproducibility, and visually they very well support the antibacterial activity. Obtained results indicate that methanolic extracts of L. sulphureus have very good antibacterial activity against all the tested bacteria except for E. coli. Nevertheless its potential should not be neglected due to its other health-beneficial effects. Introduction Laetiporus sulphureus, i.e. sulphur polypore, is an edible mushroom which has a cosmopolite distribution (mainly in Europe and North America). Even though it produces edible and recognizable bright yellow fruiting bodies, it is not widely used in nutrition. Nevertheless, its potential has been recognized in diet and traditional medicine of Anatolian people, where it has been used successfully. L. sulphureus has been the subject of numerous studies which demonstrated its biological activity (antimicrobial, antioxidant) and determined a number of metabolites which may be responsible for this activity. However, any additional information that could indicate of how these activities are linked together with bioactive metabolites is of great importance. In addition, growing trend of multidrug resistance of a number of bacteria indicates that new preliminary ideas for the eradication of bacteria are necessary. Therefore the objective of this study was to evaluate the antibacterial activity of methanolic extracts of edible mushroom L. sulphureus out of three different localities using bioautography method. Since L. sulphureus is an edible mushroom, with proven antibacterial activity its perspective as an antimicrobial agent should be further analyzed. The comparative study of antibacterial activity from edible mushroom Laetiporus sulphureus (Bull.Fr.) Murill from three localities using bioautographic method Results and Discussion: The obtained results indicate the effectiveness of the methanolic extracts against the tested bacteria, as well as whether there is difference in the activity depending on the locality of the collected mushroom. Methanolic extracts were obtained by previously optimized procedure out of lyophilized and grinded fruiting bodies. Different concentrations of the extracts (in rage from 0.24 to 2.38 mg/mL) were applied on TLC plates and left to wither. Afterwards, they were immersed in freshly prepared overnight bacterial suspensions, and allowed to dry. The plates were incubated for 24h at 37°C, sprayed with piodonitrotetrazolium violet colour, stored for another 3h and sprayed with 70% ethanol to stop bacterial growth. White inhibition zones of different size on a pinkish background (indicates the microbial growth) were indicative of antimicrobial activity. Our results indicate that all the extracts exhibited antibacterial activity in a dose dependent manner. The highest concentration was the best at inhibiting bacterial growth. From the Table 1. it can be concluded that inhibitory values were fairly uniform amongst three different methanolic extracts, with L. sulphureus H having the best antibacterial activity. Very good antibacterial activity may be due to the high content of total phenolic compounds in methanolic extract (Petrovic et al., 2014). Acknowledgment. The authors are grateful to the Ministry of Education, Science and Technological Development of Serbia for financial support (grant No. 173032). Concluding remarks: This investigation highlights alternatives to be explored for the treatment of bacterial infections.